Goofy edge-finder, or is it me?

[kb58]

I have an edge finder and know how to use it, one with a 0.200" cylinder at its end where you move into the work until the magnetic piece shifts. No problem.

I was talking to a neighbor who has a Sherline setup and saw that he had an edge-finder that I couldn't figure out how it's supposed to be used. Instead of a small cylinder portion at the bottom end, it's cone shaped. Depending where on the cone you contact the work, how does he know how much offset to subtract off? Even more puzzling is that the whole thing is maybe 2" long, and the center 1.5" portion of it, located above the cone-shaped magnetic end, is connected to the upper part (that goes into a spindle) by another magnetic connection. So, the entire edge finder assembly has two magnetic couplers, one for the top and one for the bottom. Please enlighten me on how this is supposed to be used.

(BTW, he unhappily related that he'd made the connecting rod for his Sterling engine the wrong length. I asked how far off it was, figuring something on the order of maybe 0.008". Nope, he said it was off by 5/16" of an inch! I can't help but wonder if he doesn't know how to use that edge finder either.)

 

[Superburban]

Sure it is not two ended? I have one that has about 1/4" straight on one end, and the cone style on the other.

 

[gradient]

I believe the cone shaped end is for locating small holes but with-out the finder rotating. Just lower the cone into the hole until it contacts the edges and move the finder in X and Y until the place where the cone is connected to the cylindrical part are aligned. You can feel the cone to be concentric with the cylindrical part of the finder to much less than a thousandth of an inch. As noted above, just reverse the finder to use the small cylinder end to find edges in the conventional way.

 

[Ed ke6bnl]

the ones I have had apart are not magnetic but have a spring the connect the top and bottom pieces forced against the center tube

 

[Cadillac]

Yep two lapped surfaces held together with a spring. Being magnetic wouldn’t work.

 

[middle.road]

Yep two lapped surfaces held together with a spring. Being magnetic wouldn’t work.

as a side note: A friend passed his father's Starrett on to me. Be sure to clean off the cosmoline and lubricate properly... ask me how I figured that one out.

 

[mickri]

Don't mean to hijack this thread but I need an edge finder. Birthday is next month so guess what I intend to get for my birthday. An edge finder. Been looking at these two at Shars I like this one the best. https://www.shars.com/products/measuring/edge-center-finders/edge-center-finder-set.
This one seems to be harder to use from what I have seen in the videos online. https://www.shars.com/products/measuring/edge-center-finders/wiggler-edge-center-finder-set

Help me spend my money. Which one should I get?

 

[mikey]

Buy this one. I have Starrett, Brown & Sharpe and Mitutoyo versions. All three work the same but the price on this Mit is ridiculous.

 

[benmychree]

I have only used the cone end to locate on center punch marks, such as the wiggler with a rod and fine, scribe like point on the other style of wigglers is used. I have been using both styles of wigglers for the most part of nearly 60 years now.

 

[kb58]

Sure it is not two ended? I have one that has about 1/4" straight on one end, and the cone style on the other.

You know what, pretty sure that exactly what he has and doesn't know it. He put it in the chuck grasping the 0.200" edged finder end... Oy.

I've never had one apart and was assuming about it being magnetic, oops.